Water quality in India is usually discussed in terms of diarrhoeal disease. That is reasonable — it is the largest and most visible burden. But there is a second pathway that receives almost no attention, and for roughly half the population it may matter more over a lifetime than the first.
Water in India is not only drunk. It is the primary medium for personal hygiene after using the toilet, and it is applied directly to the perineum, multiple times a day, by most of the population. If that water carries faecal organisms, the exposure is not incidental. It is direct, repeated, and anatomically precise.
Until recently this was a plausible hypothesis with no direct evidence behind it. That has changed.
The scale of the exposure
India’s water infrastructure is better than it was and worse than headline figures suggest.
Coverage statistics for “improved” water sources are high. The more demanding measure — safely managed drinking water, meaning an improved source located on the premises, available when needed, and free from contamination — tells a different story. Under this definition, fewer than half of rural Indians have access.
Groundwater supplies roughly 85% of rural and 48% of urban drinking water, drawn from over 30 million access points, and extraction stress is severe: around two-thirds of India’s districts are affected by significant depletion. Falling water tables push wells toward contaminated strata and increase the pathogen load in what comes up.
Contamination events are not rare. Between January 2025 and January 2026, sewage contamination of drinking water sickened at least 5,500 people across 26 cities and towns, with 34 documented deaths. In most cases the cause was ageing or poorly laid water pipelines running close to sewage lines.
The organism used worldwide as the indicator of faecal contamination in water is Escherichia coli — which is also the organism causing the large majority of urinary tract infections.
Two routes, and they are not equally well supported
Contaminated water could reach the urogenital tract two ways. They deserve separate treatment because the evidence behind them differs substantially, and conflating them is how this argument gets overstated.
Route one: direct application during hygiene
Water is the primary cleansing medium after urination and defecation across most of India — a lota, a mug, or the hand. Where that water carries faecal organisms, washing can transfer them across the perineum toward the urethral opening. The anatomical distance is small and the exposure is repeated daily.
This is the better-supported route, and in 2024 it gained direct microbiome-level evidence.
A prospective cohort study published in BMC Infectious Diseases followed 436 adolescent girls in western Kenya for 18 months, characterising their vaginal microbiomes by 16S rRNA sequencing at multiple time points. Adjusting for intervention arm, age, socioeconomic status, sexual activity, school-level WASH and rainfall, the researchers found:
- Odds of CST-I — the Lactobacillus crispatus-dominant, most protective community state — were higher among participants using piped water compared with pond water
- Odds of CST-I were lower among those using traditional pit latrines compared with flush toilets
- Coliform relative abundance was higher among participants relying on stream water, and higher with pit latrines
- Increased rainfall was associated with decreased odds of CST-I
- Taxa associated with water source and latrine type included vaginal organisms, opportunistic pathogens, and urinary tract pathobionts
That is the clearest demonstration available that household water source and sanitation type track with the composition of the vaginal microbiome — including the specific protective state that matters for infection risk.
It is a Kenyan cohort, not an Indian one, and it is observational. Both caveats are real. But the exposure it describes is substantially more common in India than in Kenya, and no comparable Indian study exists.
Route two: ingestion and systemic effects
It is sometimes argued that drinking contaminated water drives systemic immune activation which in turn shifts the vaginal microbiome away from Lactobacillus dominance.
We are not aware of any study that demonstrates this sequence. The Indian water-quality literature documents contamination and its enteric consequences thoroughly but does not examine vaginal microbiota. This route should be treated as a mechanistic hypothesis, not an established pathway, and anyone presenting it as settled is going beyond the evidence.
The Indian hygiene-practice evidence
Alongside the Kenyan microbiome data, there is Indian work on hygiene practices and reproductive tract infection — using symptom and diagnostic endpoints rather than sequencing.
A hospital-based cross-sectional study of 558 reproductive-age women in Odisha found that 62.4% had at least one of three tested reproductive tract infections, with bacterial vaginosis the most prevalent at 41%, and examined menstrual hygiene practices as determinants.
A population-based assessment of 3,952 girls and women across two rural Indian districts examined WASH exposures against self-reported reproductive tract infection symptoms, and found that associations varied across reproductive life stages.
A cross-sectional study of 242 indigenous adolescent girls in Bangladesh during a period of seasonal water scarcity found self-reported UTI symptoms in 35.5% and BV symptoms in 28.9%, with source of water used for hygiene and perceived water quality both significantly associated with symptom prevalence.
These studies use weaker endpoints than sequencing. Together with the Kenyan cohort, they describe a consistent pattern.
Why scarcity compounds it
Water scarcity does not only reduce the quantity available. It degrades what gets used for hygiene in specific ways:
- Water is rationed and reused, sometimes across household members
- It is stored for extended periods, often in open containers, where bacterial counts rise
- It is drawn from visibly unsafe sources — ponds, step-wells, hand pumps near latrines — when nothing better is available
This explains something that otherwise looks puzzling: why infection rates stay high in areas with nominal water “access.” The water may be physically present and microbiologically unsuitable for intimate hygiene. Access and safety are different measurements, and only one of them is usually reported.
What this means mechanistically
If the association holds, the chain runs roughly: contaminated water used for perineal hygiene, leading to repeated introduction of faecal organisms to the vulvovaginal area, leading to competition with the resident Lactobacillus community, leading to a shift away from CST-I toward the diverse, low-lactobacillus state, and so to loss of colonisation resistance and increased susceptibility to urinary and reproductive tract infection.
The loss of resistance step is well characterised. A Lactobacillus-dominant community produces lactic acid at concentrations shown to inactivate all seventeen bacterial-vaginosis-associated species tested under anaerobic conditions, while sparing the lactobacilli themselves. Lose that community and the chemical barrier goes with it.
There is also a more specific route. A 2017 mouse study found that brief bladder exposure to Gardnerella vaginalis — an organism characteristic of the diverse state — triggered dormant intracellular E. coli to emerge and cause recurrent infection, with kidney injury persisting after the Gardnerella was cleared. L. crispatus exposure produced no such effect. That is a mouse model and has not been shown in women, but it offers a plausible link between the vaginal community state and recurrent urinary infection specifically.
What is established, what is plausible, what is untested
Established. Household water source, sanitation type and rainfall are associated with vaginal microbiome composition, including CST-I prevalence and coliform abundance, in at least one prospective sequencing cohort. WASH exposures and hygiene practices are associated with reproductive tract infection symptoms and BV prevalence in Indian and Bangladeshi populations. Loss of Lactobacillus dominance is associated with increased infection susceptibility.
Plausible. That mechanical transfer of faecal organisms during water-based perineal hygiene is a principal route linking water quality to urogenital colonisation in India.
Untested. That ingestion of contaminated water alters vaginal microbiota through systemic effects. That either route operates at the magnitude proposed in Indian populations specifically — because the sequencing study is Kenyan and the Indian studies use symptom endpoints.
The study that should exist
The gap is specific and the study that would close it is not complicated: a cross-sectional comparison of vaginal microbiome composition, UTI prevalence and uropathogen resistance profiles among Indian women stratified by household water source, with coliform testing of the water actually used for hygiene and structured assessment of practice.
Two or three hundred women across paired communities — one with documented safe water, one without — would be enough to establish whether the Kenyan finding replicates in India.
Given that under half of rural India has safely managed water, and that water-based perineal hygiene is near-universal, the exposed population is among the largest of any modifiable risk factor in women’s health in this country. It is odd that nobody has measured it.
Neuriva Life Sciences is a DPIIT-recognised start-up working on microbiome-based approaches to urogenital health. This article is general information and is not medical advice.
Sources
- Czapar AE, Paul S, Zulaika G, et al. BMC Infect Dis. 2024;24(1):1419. doi:10.1186/s12879-024-10313-3
- Torondel B, Sinha S, Mohanty JR, et al. BMC Infect Dis. 2018;18:473
- van Eijk AM, Sivakami M, Thakkar MB, et al. PLoS One. 2017;12(12):e0188234
- Sarker AR, et al. Health Sci Rep. 2024;7(5):e2107. doi:10.1002/hsr2.2107
- O’Hanlon DE, Moench TR, Cone RA. BMC Infect Dis. 2011;11:200. doi:10.1186/1471-2334-11-200
- Gilbert NM, O’Brien VP, Lewis AL. PLoS Pathog. 2017;13(3):e1006238. doi:10.1371/journal.ppat.1006238
- WHO/UNICEF Joint Monitoring Programme. Progress on drinking water, sanitation and hygiene: 2017 update and SDG baselines
- UNICEF India. Clean drinking water and sanitation programme. 2022
